Big companies hate rev share, which is essentially what value based pricing model is. Rev share pricing is great for getting small, money-conscious people in the door, but there is a threshold as you get larger where it becomes more cost-effective for the client to go with standard billing.

Substack's been running into this problem, where it's easy to get people to try it out, but as a content creator gets popular the rev share amount becomes greater than the cost to hire an agency and "self-host". Someone making $1mm/yr is going to chafe at a $200k rev share when an agency at $50k/yr retainer can do a similar job.

Unrelated to that but related to the main topic: it's interesting that people treat FOSS consulting as a weird beast and ignore the thousands of successful WordPress/Drupal/etc. consultants and agencies. There's a lot to be learned from analyzing their strategies!